This invention relates to systems and methods used in controlled-environment agriculture. More particularly, it relates to methods, and means to regulate the environment in a greenhouse where food and flower production is carried out, and the environmental conditions surrounding the greenhouse are less than optimal. It is directed to carrying out the regulation of the environment in the greenhouse with maximum efficiency, using the least external energy and providing economies in the process.
Improved technologies, genetic manipulation, and agriculture practices have dramatically increased worldwide food production, usually at a cost of increased energy use. A combination of factors such as poor climate, problem soils, increased energy costs, and other economic and political factors have caused many of the poorest countries to actually show decreased food production.
The highest food production increases of the past have been obtained in the most favorable environments--areas with good soils, controlled water supplies, the least risk from pest damage, and easy access to markets. While it is likely that much of the production increases in the next few decades will come from these same favored areas, an increasing proportion must come from regions less well endowed with favorable natural and biological environments or from controlled-environment agriculture.
Controlled-environment agriculture can modify or eliminate many of the natural barriers to food production, and the challenge of the future will be to broaden the base of increased food production to include areas which are not endowed with natural and economic resources.
Controlled-environment agriculture is the cultivation of vegetable, ornamental, and other plants in an enclosure within which those environmental factors which are generally recognized as influencing plant growth, maturation, and productivity, are systematically timed, programmed and carefully controlled. Typically the controlled growth factors included the intensity, duration, and spectral distribution of insulation, the temperature, humidity, and flow rate of the air, its carbon dioxide concentration and the composition and temperature of the nutrient supplied to the growing plants. This later parameter is easily controlled in those installations in which hydroponics techniques are employed, as the nutrient solutions used with hydrophonics may readily be analyzed for chemical composition and replenished as necessary to maintain their compositions within the desired ranges of variation of the constituents. This invention is directed to the more difficult environmental control problems and particularly those connected with air temperature, humidity, circulation, and insulation.
A greenhouse is inherently a structure that is greatly influenced by the amount and control of insulation. Various methods have been devised to accomplish this. Greenhouses usually provide large surface areas of translucent or transparent materials. During certain portions of the day the sun passes through these materials and has a strong effect on the environment within the greenhouse facility. Most greenhouses have means for regulating the amount of insulation and this is often done with shades, blinds, coatings, or black liquids.
U.S. Pat. No. 4,195,441--Baldwin, is typical of a more advanced solar greenhouse having means for shading and controlling insulation as well as being representative of many other facets of the typical "controlled environment agriculture facility".
U.S. Pat. No. 4,163,342--Fogg et al., discloses another controlled environment agricultural system in which insulation is not a factor and light is provided artificially as a means of very finitely controlling its amount and intensity.
Still another U.S. Pat. No. 3,807,088`--Jones, shows a controlled environment facility in which evaporative pads are extended across an end of the building providing a measure of air temperature and humidity control.
The above recited patents, together with U.S. Pat. No. 3,446,272--Gaines, are representative of the considerable extent of specific detail to which the prior art has developed this field of invention. There is good reason for this since what might appear to be minor details and variations in means and methods are often, to the contrary, very important in providing the most successful operations.
As stated at the beginning of this background discussion, the criteria of an efficient energy use has become of major significance with recent increases in energy cost. Therefore, means which increase this factor take on great significance in creative innovative activity.